During the ceremony the Queen met veteran Umrao Singh, who received the Victoria Cross for action in Burma.

She also met Suleiman Omer Kujog, the son of a Somali sergeant who was killed in action.

Mr Kujog, 64, said it should have been constructed earlier.

Rajimbar Singh Dhatt served Britain in 1941

"It was too late. It should've happened before," he said.

"It reminds me of my father. It reminds me of the time I was one and I grew up as an orphan. It reminds me of the evils of war."

The ceremony included a mounted escort from India and Pakistan and a lament by the pipers of the Royal Gurkha Rifles.

Baroness Flather, of the Memorial Gates Trust, which raised £2.7m towards the monument, told the BBC the contribution of millions of volunteers from Africa, the Caribbean and the Indian subcontinent had been largely overlooked.

She said: "Somehow they have been erased from the memory of people here.

"We need to inform the young ethnic minority children about this contribution. We need to inform everybody else as well."

Rajimbar Singh Dhatt from Hounslow, west London, agreed the memorial was long overdue.

"This is very important for us. It's important for the new population because it shows the multiracial and multicultural society."